R, how can I make a heatmap out of a simple matrix?

Question

Say I have a simple matrix A generated by

 A = matrix(c(1,2,3,4,5,6,7,8,9),nrow=3,ncol=3)

Now, my goal is to make a heatmap out of A, such that each number is replaced by a colour field. How to do that? I tried

heatmap(A)

but it produced three coloured stripes instead of 9 distinct fields.

you should look at the method geom_tile in ggplot2 package (as an example) and quite likely convert your matrix to a data.frame. This link can be helpful: https://learnr.wordpress.com/2010/01/26/ggplot2-quick-heatmap-plotting/ — Picarus, Jan 07 '16 at 21:59

score 8 · Accepted Answer · answered Jan 07 '16 at 22:09

8

One of the possibilities that have not been described in the solutions referred to in the comments consists in using the pheatmap package:

library(pheatmap)
A <- matrix(c(1,2,3,4,5,6,7,8,9),nrow=3,ncol=3)
pheatmap(A, cluster_rows = FALSE, cluster_cols = FALSE)

which gives:

answered Jan 07 '16 at 22:09

RHertel

1 Answers1